The invention relates to methods and equipment for reporting charging information to mobile subscribers, including, for example reporting the amount of available credit to prepaid subscribers. In mobile communications systems, such as GSM, the use of prepaid SIM (Subscriber Identity Module) cards is increasing. Prepaid SIM cards relieve the network operators of credit losses. They enable parents to set an upper limit for the telephone bill of their children beforehand. As a third benefit, they enable roaming subscribers to pay their local calls with local tariffs, whereas the use of the SIM card of their home operator results in paying international tariffs to their home network and back.
A problem with prepaid SIM cards is that current mobile stations (handsets) are not provided with means for automatically displaying credit-related information, such as the current credit status, immediately after the end of a call. Some operators allow the subscribers to call an Interactive Voice Response (IVR) service which reports the available credit by synthesized speech. Such a service causes another problem: using the IVR causes a significant amount of overhead traffic in the radio interface. This non-chargeable traffic consumes resources which could be better spent on chargeable calls.